Voltage regulator tube



1958 A. J. STOKES ETAL 2,864,023

' VOLTAGE REGULATOR TUBE Filed Aug. 22, 1956 lllll Rizal,

ATTORNEY United States Patent assao'zs VOLTAGE REGULATOR TUBE Application August 22, 1956, Serial No. 605,556 7 claims. or. 313-148 This invention relates to a voltage regulator tube of the type containing ionizable gas.

Voltage regulator tubes of the so-called corona discharge type commonly comprise an outer sleeve, which serves as the cathode, a concentrically disposed inner anode rod, and'an ionizable gas under pressure filling the sleeve. Such tubes are used for regulating voltages several hundred to many thousands of volts, such as in regulated voltage power supplies in color television receivers, for example. a

One of the disadvantages of prior tubes of this general type has been the lack of a convenient arrangement for adjusting the gas pressure over a sufficiently wide range after the tube has been filled, so as to adjust correspondingly the ionization voltage of the tube.

This disadvantage is avoided in the present invention, which is directed to a voltage regulator tube having novel provision for adjusting the gas pressure in the tube after filling. V a v p Accordingly, it is an object of the present invention to provide a voltage regulator tube containing ionizable gas which has a novel arrangement for adjusting the gas pressure after filling.

It is also an object of this invention to provide such a voltage regulator tube having novel provisionfor conveniently adjusting the gas pressure, ;after filling, over a wider rangethan has been done heretofore. j

Further Objects and advantages of this invention will be apparent from the following description of a preferred embodiment thereof, which is illustrated in the accompanying drawing.

In the drawing, the single figure is an enlarged longitudinal sectio through the voltage regulator tube according to the present invention.

Referring to the drawing, the tube comprises an outer cylindrical sleeve 10 which serves as the cathode and which may be of iron or other suitable conductive material. Concentrically disposed within the cathode sleeve 10 is a thin elongated rod 11 which serves as the anode and which in one practical embodiment may be of stainless steel. A cup-shaped insulator 12 of alumina or other suitable insulating material is received in one end of the sleeve 10 and provides a support for the corresponding end of anode 11. The insulator 12 does not hermetically seal this end of sleeve 10, so that gas can flow around this insulator into and out of sleeve 10. If desired, the insulator 12 may be formed with through passages 12a for this purpose.

A tubular ceramic insulator 13 is secured in gas-tight fashion to the opposite end of the sleeve 10 by means of a flanged annular plate 14 aflixed to that end of sleeve 10 and an annular member 15. The anode 11 projects into insulator 13 and presents an enlarged transverse shoulder 11a therein, which is engaged by one end of a compression coil spring 16. The opposite end of spring 16 is seated against the closed end of a metal cup 17, which is secured within the bore of insulator 13 in gastight fashion by a suitable glass-to-metal seal, such as Kovar. A threaded bolthas its head 18 connected to cup 17 and its threaded stem 19 projecting beyond the insulator 13 for connection in the electrical circuit in which the tube is to be used. The spring 16 snugly encircles the end of anode 11 to support it there and also presses the anode to the left in the drawing into its seat in the insulator 12 at its opposite end. .1

A metal ring 20 snugly encircles the left end of the sleeve 10 in the drawing and aflat rigid metal plate 21, which is attached to this'ring, extends transversely across this end of sleeve 10. This plate-presents a flat face 21a facing away from sleeve 10 which has a surface several times the cross-sectional area of the space between sleeve 10 and anode 11. Plate 21 is formed with a central opening 21b aligned with the .bore of sleeveilt), sothat the outer end'of insulator 12 is exposed at this opening. A substantially flat, planar, metal diaphragm 22 is positioned in closely spaced, confronting, face-to-face relationship with respect to plate 21. Diaphragm 22 and plate'21 are secured to each other in gas-tight fashion completely around their respective peripheries so that together they define a chamber of appreciable volume in certain adjusted positions compared to the volume of the gas cham ber within sleeve 10. In one practical embodiment, the maximum volume of the chamber between diaphragm 22 and plate 21 is 25% of the volume of the gas chamber within sleeve 10; 1

Diaphragm-22 is formed with a circular corrugation 23 for strengthening purposes and this corrugation is engaged by the front end of a follower 24 which is threadedly mounted on the threaded inner end of a rotatable shaft 25. Shaft 25 is supported rotatably by a cup-shaped back cover'member 26, which is secured to a front cover plate 27 welded to the ring 20. v t I a The diaphragm 22 is formed with a rearwardly projecting frusto-conical boss 22a at whichis seated in fluidtight relationshiputhe complementary.frusto-conical inner end 28a of a filler tube 28., Thus, the filler, tubev28 extends through the diaphragm for fluid communication with the chamber defined by the diaphragm and plate21. After filling, this tube pinchedoifand sealed at 28b.

A rigidbacking' plate 29 is mounted on the annularly cut-away front end 24a of follower 24 and extends immediately behind the major portion of diaphragm 22 to reinforce the latter in the event that gas pressure should tend to cause the diaphragm to buckle. Plate 29 is formed With a circular opening 29a which freely receives the boss 22a on diaphragm 22.

Before being put into use, the described voltage regulator tube is first evacuated and then filled with a suitable ionizable gas, such as hydrogen, to the desired pressure which may be above atmospheric. Then the filling tube 28 is sealed off. Now the gas pressure within the voltage regulator tube can be adjusted over a rather wide range simply by turning the shaft 25. By virtue of the threaded engagement between shaft 25 and its follower 24, the follower causes the diaphragm 22 to move toward or away from plate 21. Since insulator 12 does not hermetically seal the end of sleeve 10, the corresponding pressure changes in the variable volume chamber defined by plate 21 and diaphragm 22 are transmitted to the gas chamber within sleeve 10, so as to vary correspondingly the ionization voltage characteristics of the tube.

A particular advantage of the present invention is that the volume of the chamber defined by plate 21 and diaphragm 22 can be varied from a maximum volume down to substantially zero, which latter condition is obtained when the diaphragm is pushed substantially fiat against plate 21. Due to the broad areas of the plate 21 and diaphragm 22 the maximum volume of this chamber is an appreciable portion of the overall gas volume in this tube, so that such a large change in the volume of this chamber is reflected as a substantial change in the gas pressure within the tube. For example, in one practical embodiment the maximum volume of the variable volume chamber between diaphragm 22 and plate 21 is onefourth that of the gas chamber within sleeve 10, and so displacement of the diaphragm 22 can cause the overall volume to vary as much as 20% below its maximum value, enabling quite a wide range of adjustment in the ionization voltage of the tube.

'Thebacking plate 29 carried by follower 24 insures against the collapse of the diaphragm 22 even at the highest pressure established in the tube.

A particular advantage of the substantially flat diaphragm construction in the present invention is that it presents a minimum surface area to the gas in the tube while still being adapted to effect a very substantial variation in the gas pressure within the tube. This is particularly important where the gas is hydrogen, which tends to diffuse through metal. Such diffusion is kept to a minimum because of the reduced surface area presented by the substantially fiat diaphragm.

It is to be understood that, while there has been de scribed herein and illustrated in the accompanying drawing a specific preferred embodiment of the present invention, various modifications, omissions and refinements which depart from the disclosed embodiment may be adopted without departing from the spirit and scope of the present invention.

We claim:

1. A voltage regulator tube comprising an envelope which defines a gas chamber having spaced electrodes and containing ionizable gas, a plate secured to one end of said envelope and extending transversely thereof, a substantially planar diaphragm secured around its periphery to said plate and away from its periphery extending in closely spaced confronting relation to said plate and defining therewith a pressure chamber, and means for adjusting said diaphragm toward or away from said plate to vary the volume of said pressure chamber and thereby vary the gas pressure in said gas chamber.

2. The voltage regulator tube of claim 1, wherein said diaphragm is movable to' engage said plate substantially completely thereacross to reduce the volume of said pressure chamber to substantially zero.

3. The voltage regulator tube of claim 2, wherein said adjusting means includes a backing plate extending behind the diaphragm in closely spaced relation thereto across the major portion of the diaphragm to prevent buckling of the diaphragm.

4. A voltage regulator tube comprising a cylindrical cathode and an anode supported coaxially Within the cathode, lonizable gas filling the space between the cathode and the anode, a rigid plate secured to one end of. the cathode and extending transversely thereof, said plate presenting a substantially fiat face having an area several times the cross-sectional area of the space between the cathode and the anode, a movable substantially planar diaphragm secured around its periphery to the periphery of said plate, said diaphragm away from its periphery extending in closely spaced confronting relation to said face of the plate and defining therewith a pressure chamber communicating with the space between the cathode and the anode, and means for adjusting said diaphragm toward and away from said plate to vary the pressure of the gas in the space between the cathode and the anode.

5. The voltage regulator tube of claim 4, wherein said adjusting means includes a backing plate extending behind the diaphragm in closely spaced relation thereto across the major portion of the diaphragm to prevent buckling of the diaphragm.

6. The voltage regulator tube of claim 4, wherein said adjusting means comprises an externally threaded rotatable member, and a follower threadedly mounted on said rotatable member and engaging said diaphragm.

7. The voltage regulator tube of claim 4, wherein said adjusting means comprises a rotatable shaft having an externally threaded portion disposed in spaced relation behind the diaphragm, a follower threadedly mounted on the threaded portion of the shaft and engaging the back of the diaphragm, and a backing plate mounted on said follower and extending in closely spaced relation to the back of the diaphragm across the major portion of the diaphragm to prevent buckling of the diaphragm.

References Cited in the file of this patent UNITED STATES PATENTS 2,378,227 Lee June 12, 1945 2,523,287 Friedman Sept. 26, 1950 2,576,100 Brown Nov. 27, 1951 

